knitting scheme development from art to science mr. arkin ng 1, dr jimmy k c lam 2 1 natalia fashion...

Knitting Scheme Knitting Scheme DevelopmentDevelopment

from Art to Sciencefrom Art to Science

Knitting Scheme Knitting Scheme DevelopmentDevelopment

from Art to Sciencefrom Art to Science

Mr. Arkin NgMr. Arkin Ng11, Dr Jimmy K C Lam, Dr Jimmy K C Lam22

11Natalia Fashion Ltd, Hong KongNatalia Fashion Ltd, Hong Kong22Institute of Textiles & Clothing, Institute of Textiles & Clothing,

The Hong Kong Polytechnic UniversityThe Hong Kong Polytechnic University

The 86th TIWC, Nov 18-21, 2008, Hong Kong

2

Outlines• Introduction and Background• Experimental Details• Results and Discussions

– Fabric dimensions and tightness– Fabric dimensions and machine gauge– Fabric dimensions and tightness factor– Fabric pilling and textile materials

• Conclusions


3

Introduction & Backgrounds

• Flat knitting is one of the most important technological Flat knitting is one of the most important technological inventions for knitwear design and production that has inventions for knitwear design and production that has gone through a lot of changes over time.gone through a lot of changes over time.

• When comparing the primary flat knitting using jacquard When comparing the primary flat knitting using jacquard steel for needle selection with the state-of-the-art machine steel for needle selection with the state-of-the-art machine for integral shape knitwear, one can readily realize the for integral shape knitwear, one can readily realize the amount of breakthroughs in this procession.amount of breakthroughs in this procession.

• The huge improvement in the efficiency of loop transfer The huge improvement in the efficiency of loop transfer has replaced the flat bed purl knitting machine with has replaced the flat bed purl knitting machine with double hook latch needles.double hook latch needles.


4

Introduction & Backgrounds

• The knitting production process evolved from cut-and-sewn piece goods knitting to fully fashion shaped knitting, and finally to integral shape knitting.

• The latest machine has completely eliminated the cutting and linking processes and put things together in one single operation.


5

Stage One: Cut and Sewn

Stage Two: Shaping

Stage Three: Integral Knitting

Stage Four: Whole Garment Knitting

Evolution of Knitwear Technology


6

Introduction & Backgrounds 2

• Despite all these technological developments in flat knitting, the key instructional method (knitting scheme) is still relied on the skill and experience of individual knitting technician.

• With increasing demand for fine gauge knitting and 3-D products, ability to produce fine and accurate knitting schemes is critical for quality assurance and production.

• Conventional knitting schemes are work of individual often lacking in consistency amongst their compliers.

• This trial-and-error approach which is sufficient for coarse gauge loose body knitting but crude on body-fitted knitting.


7

What is Knitting Scheme ?

• Knitting scheme is the statement used to knit the garment parts which is expressed in terms of courses (fabric length), needles width (fabric width) and fashioning frequencies.

• A swatch (a small piece of fabric) in correct knitting instruction and knitting tension is normally prepared before bulk production.

• One of the useful methods to determine the stitch tension is to stretch the fabric widthwise to its utmost limits manually and measure the dimension of 10 wales board.


8

What is Knitting Scheme2 ?

• The number of wales and courses per cm after finishing which is determined from the swatch to prepare the knitting scheme.

• The swatch is set and the knitting scheme is written according to the stitch density and the style of knitwear.

• Typical knitting scheme is shown in Figure 1


9

Figure 1 Typical Knitting Scheme on Fully Fashion Panel


10

Experimental Details• A hand knit flat bed machine with 36 inches

width, 12 gauge and 432 needles will be used to produce a jersey plain knitted fully fashion panel.

• Five different materials and three different knitting tensions and three different machine gauges were used, total of 45 samples were produced.

• The fabric samples were knitted into three different tightness as suggested from the industry and shown in Table 1.


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Table 1 Fabric density and tightness.

Machine GaugeKnitting Tension

Tightness(measured in 10 wales)

Tightness(measured in 10 wales)

5G Tight 3-4/8” 8.09 cm

5G Normal 3-7/8” 9.84 cm

5G Loose 4-2/8” 10.79cm

7G Tight 2-4/8” 6.35 cm

7G Normal 2-6/8” 6.98 cm

7G Loose 3-0” 7.63 cm

12G Tight 1-3/8” 3.49 cm

12G Normal 1-4/8” 3.81 cm

12G Loose 1-5/8” 4.12 cm


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• The three different tensions (tight, normal and loose) for three different gauges (5G, 7G and 12G) for five materials (acrylic, cotton, pima cotton, cashmere and wool) were converted into tightness factor so that fabric dimensions and fabric density can be compared,

• Table 2 shows results for acrylic fibre.


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Table 2 Knitting tension, loop length and tightness factor for acrylic fabric

Machine Gauge

Knitting Tension

Yarn Tex Average loop length (mm)

Tightness factor

5G Tight 285.6 15.90 1.06

5G Normal 285.6 16.47 1.03

5G Loose 285.6 16.62 1.02

7G Tight 142.8 9.65 1.24

7G Normal 142.8 10.57 1.13

7G Loose 142.8 10.77 1.11

12G Tight 71.4 5.80 1.46

12G Normal 71.4 5.86 1.44

12G Loose 71.4 6.27 1.35

Results and Results and DiscussionsDiscussionsResults and Results and DiscussionsDiscussions


15

Fabric Dimensions and tightness

• Figures 1 & 2 showed the fabric dimensions under different tensions for different fibres for 5G fabric.

• Figure 1 showed that the courses per cm decease if the average loop length. In other words, the three different knitting tensions (tight, normal and loose) will affect fabric course density.

• The higher is the knitting tension (tight knitting), the smaller is the loop length and the higher is the course density.


16

Courses/cm V.S. Loop Length/stitch (mm) at 5 Gauge

3

3.5

4

4.5

5

13 14 15 16 17Loop Length/stitch (mm)

Cou

rses

/cm

2/28Nm Acrylic

40/2NeC Cotton(combed)

10/1Nec Cotton(pima)

2/28Nm Cashmere

2/28Nm Wool

2/48Nm Wool

Figure 1: Courses per cm and loop length on 5G machine


17

Wales/cm V.S. Loop Length/stitch (mm) at 5 Gauge

2

2.5

3

3.5

13 14 15 16 17

Loop Length/stitch (mm)

Wal

es/c

m

2/28Nm Acrylic

40/2NeC Cotton(combed)

10/1Nec Cotton(pima)

2/28Nm Cashmere

2/28Nm Wool

2/48Nm Wool

Figure 2: Wales per cm and loop length on 5G machine


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• Both courses per cm and wales per cm (Fig. 1 & 2) show inversely relationship to fabric loop length under different knitting tension on these five different textile materials.

• Figure 3 showed this relationship with empirical formula after we plotted all data on the same chart.

• Figure 4 showed the stitch density (wales/cm X courses/cm) are inversely proportional to loop length square


19

Loop length & fabric density

courses/cm = -0.2626x + 7.985

R2 = 0.5796

wales/cm = -0.1682x + 5.0755

R2 = 0.6068

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

10 11 12 13 14 15 16 17 18

loop length (mm)

fab

ric

den

sity

(cm

)

Figure 3: Fabric density to loop length for these five textile materials in 5G machine


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Stitch densityStitch density = -16.477x + 397.91

R2 = 0.7398

0

50

100

150

200

250

300

4 6 8 10 12 14

Loop Length Sqaure

Sti

tch

Den

sity

(w

pcm

X c

pcm

)

Figure 4: Stitch density to loop length square


21

Fabric dimensions and machine gauge

• The fabric dimensions (wales/cm and courses/cm) will be affected by machine gauge under different knitting tension as shown in Figure 5.

• It can be seen that both coarse gauge (5G) and fine gauge (12G) fabric samples show inversely relationship between loop length and courses/cm


22

Effect of machine gauge and course density

3

4

5

6

7

8

9

10

5 7 9 11 13 15 17

Loop length (mm)

co

urs

es

/cm

5G Acrylic

7 Gauge Acrylic

12G Acrylic

Figure 5: Relationship between courses/cm and loop length on acrylic fabric for different gauges


23

Fabric dimensions and tightness factor

• In order to find out the effect of yarn count (tex), machine gauge on fabric dimensions, the fabric loop length is converted into tightness factor (TF).

• Tightness Factor = Sqrt(Tex)/loop length.

• Figure 6 show the tightness factor to loop length for the acrylic fibres under three different machine gauges.


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Acrylic Fiber

1.5

2.5

3.5

4.5

5.5

6.5

7.5

8.5

9.5

0.80 0.90 1.00 1.10 1.20 1.30 1.40 1.50

Tightness Factor

coru

ses

per

cm

7 G

12G

5G

Figure 6 Courses density to tightness factor on acrylic fibres


25

Fabric Pilling and Textile Materials

• Pilling is a fabric surface fault in which “pills” of entanglements fibres cling to the cloth surface, giving a bad appearance of garment.

• The International Fabricare Institute defines pilling as “the formation of small tangles of fibres or balls on the surface of fabric”.


26

Fabric Pilling and Textile Materials

• Figure 7 showed the effect of fabric pilling for different textile materials on different machine gauges.

• It can be shown that textile materials play an important role on fabric pilling.

• The wool fibres give a lower pilling rate because of the scales nature of wool material which will trap the loose broken fibres on the fabric surface.

• Both cotton and cotton pima fibres give a higher pilling rate because of the smooth and fine surface of these cotton fibres. Only a small amount of broken fibres are shown on the surface and these loose fibres are easily fall off from the fabric surface.


27

Pilling Test for different materials

0

1

2

3

4

5

6

Acrylic Cotton Cotton Pima Cashmere Wool 2/28 Wool 2/48

Fabrics

Pil

lin

g R

ate

5G

7G

12G

Figure 7 Pilling test for different fibres on different machine gauges


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Pilling and Materials• The relationship between pilling and

machine gauge is not obviously to determine.

• For wool fabric, the coarser is the machine gauge (5G), the lower is the pilling rate as the open structure of coarse gauge machine will increase the number of broken fibres on the fabric surface.


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Conclusions• This paper shows the results of commercial knitting

scheme on different fibres (wool/acrylic/cotton/cashmere) under three different knitting tensions (tight/normal/loose).

• Results show that different materials will affect the final fabric dimension in terms of knitting tensions and machine gauge.

• Tightness factor is a good indicator to predict different yarn linear density and fabric loop length.

• Fabric pilling is directly affected by different textile fibres and wool fibres show a poor pilling than cotton fibre.

• However, no direct relationship between fabric pilling and machine gauge is found.


30

Acknowledgements• The authors like to thank for the

Natalia Fahsion Ltd to provide the data for experiment and the support from the University in term of Teaching Company Scheme for this project.

knitting scheme development from art to science mr. arkin ng 1, dr jimmy k c lam 2 1 natalia fashion...

Documents

primary flat knitting

integral knitting stage

integral shape knitting

knitting production

knitting scheme development

fashion shaped knitting

accurate knitting schemes

conventional knitting